A flaw was found in Keycloak, where it does not properly validate URLs included in a redirect. An attacker can use this flaw to construct a malicious request to bypass validation and access other URLs and potentially sensitive information within the domain or possibly conduct further attacks. This flaw affects any client that utilizes a wildcard in the Valid Redirect URIs field.

Acknowledgements:

Special thanks to Axel Flamcourt for reporting this issue and helping us improve our project.